netdev - [PATCH 08/10] net: wwan: core: implement TIOCINQ ioctl

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  8 Jun 2021 07:02:39 +0300
From:   Sergey Ryazanov <ryazanov.s.a@...il.com>
To:     Loic Poulain <loic.poulain@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-wireless@...r.kernel.org
Subject: [PATCH 08/10] net: wwan: core: implement TIOCINQ ioctl

It is quite common for a userpace program to fetch the buffered amount
of data in the rx queue to avoid the read block. Implement the TIOCINQ
ioctl to make the migration to the WWAN port usage smooth.

Despite the fact that the read call will return no more data than the
size of a first skb in the queue, TIOCINQ returns the entire amount of
buffered data (sum of all queued skbs). This is done to prevent the
breaking of programs that optimize reading, avoiding it if the buffered
amount of data is too small.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@...il.com>
---
 drivers/net/wwan/wwan_core.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 9346b2661eb3..d5a197da4a41 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -12,6 +12,7 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/termios.h>
 #include <linux/wwan.h>
 
 /* Maximum number of minors in use */
@@ -618,6 +619,30 @@ static __poll_t wwan_port_fops_poll(struct file *filp, poll_table *wait)
 	return mask;
 }
 
+static long wwan_port_fops_ioctl(struct file *filp, unsigned int cmd,
+				 unsigned long arg)
+{
+	struct wwan_port *port = filp->private_data;
+
+	switch (cmd) {
+	case TIOCINQ: {	/* aka SIOCINQ aka FIONREAD */
+		unsigned long flags;
+		struct sk_buff *skb;
+		int amount = 0;
+
+		spin_lock_irqsave(&port->rxq.lock, flags);
+		skb_queue_walk(&port->rxq, skb)
+			amount += skb->len;
+		spin_unlock_irqrestore(&port->rxq.lock, flags);
+
+		return put_user(amount, (int __user *)arg);
+	}
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
 static const struct file_operations wwan_port_fops = {
 	.owner = THIS_MODULE,
 	.open = wwan_port_fops_open,
@@ -625,6 +650,10 @@ static const struct file_operations wwan_port_fops = {
 	.read = wwan_port_fops_read,
 	.write = wwan_port_fops_write,
 	.poll = wwan_port_fops_poll,
+	.unlocked_ioctl = wwan_port_fops_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = compat_ptr_ioctl,
+#endif
 	.llseek = noop_llseek,
 };
 
-- 
2.26.3